U.S. Pat. No. 4,739,712 issued Apr. 26, 1988 and owned by the assignee of this invention discloses apparatus for supplying an air curtain to a pit containing combustible material such as stumps, tree limbs, trees and other debris to be burned. The apparatus of U.S. Pat. No. 4,739,712 is usable in connection with a pit which simply constitutes an excavated hole in the ground or may be used in conjunction with this invention.
Material to be burned normally is deposited in a debris burning pit by heavy apparatus such as front end loaders and the like. Such loading devices may cause the walls of an earthen pit to collapse and to partially fill the pit. If burning is in process during loading operations a wall collapse interferes with efficient burning and leads to time consuming and expensive clean-up operations.